Corrosion inhibition in water system



May 5, 1970 R. M. SILVERSTEIN ETAL 3,510,436

CORROSION INHIBITION IN WATER SYSTEM Filed (Jot. 51, 1968 5 Sheets-Sheet2 DIOC TYL (ETHYLENE OXIDE ADDUCT) PYROPHOSPHATE,

7o-- MERCAPTOBENZOTHIAZOLE AND ZINC AT pH 6 0 ppm treatment 98.5 mpy 2ppm MET-6 ppm Zn 49.0 mpy 6 ppm Zn 82-0 mpy |2.5 ppm MBT-37.5 ppm Zn45-0 mpy 50 ppm Zn 42.0 mpy DIOCTYL (ETHYLENE OXIDE ADDUCT)PYROPHOSPHATE g o 50 5 p... & E 5 4o DIOCTYL (ETHYLENE OXIDE ADDUCT) aPYROPHOSPHATE PLUS 6 ppm Zn .J :2 E E 20 I-ZJ DIOCTYL (ETHYLENE OXIDEADDUCT) W PYROPHOSPHATE PLUS 2 ppm MET-6 ppm Zn l l I 0 2o 40 so so I00TOTAL TREATMENT CONCENTRATION, ppm.

ATTORN EYE May 5, 1970 Filed 001:. 31. 1968 EEEFFERENTIAL AVERAGEPENETRATTOMmpy R. M. SILVERSTEIN AL CORROSION INHIBITION IN WATER SYSTEMs Sheets-Sheet 5 DIOCTYL (ETHYLENE OXIDE ADDUCT) PYROPHOSPHATE,MERCAPTOBENZOTHIAZOLE AND ZINC AT pH 7 ppm Tr oatment ll0-5 mpy 2 ppmMBT 83-0 mpy 2 ppm MBT- 6 ppm Zn-48-O mpy DIOCTYL (ETHYLENE OXIDEADDUCT) PYROPHOSPHATE DIOCTYL(ETHYLENE OXIDE ADDUCT) PYROPHOSPHATE PLUSZppm MBT 2.0-

DIOCTYL (ETHYLENE OXIDE ADDUCT) 0 PYROPHOSPHATE PLUS \0 2 ppm MET-6 ppmZn l I l I 0 2O 6O I00 TOTAL TREATMENT CONCENTRATION,ppm

ATTORNEYZ'B United States Patent 01 ifice 3,510,436 Patented May 5, 1970US. Cl. 252389 21 Claims ABSTRACT OF THE DISCLOSURE The presentdisclosure relates to corrosion inhibition in water systems,particularly industrial water systems and especially those in whichcirculating water is present. According to the present invention, acomposition comprising at least one water-soluble, organic derivative ofan acid of phosphorus in combination with a water soluble zinc compoundand/or mercaptobenzothiazole is added to the system to be treated.

This application is a continuation-in-part of co-pending applicationSer. No. 450,220 filed Apr. 22, 1965, and now abandoned.

BACKGROUND OF THE INVENTION The technology of water-treatment, whetherit be for industrial or domestic purposes has reached a high degree ofsophistication. The industry is constantly seeking new materials toeither replace those which are currently being used or to enhance thosealready in use.

The materials or composition must fulfill a number of prerequisites ofwhich may be mentioned watersolubility, non-toxicity to both humans andmarine-life, hydrolytic stability and of course, corrosion inhibitingand anti-scale forming properties.

In view of the recent Federal and state limitations, the toxicity ofthese materials has become a critical consideration. Chromate treatmentshave found very successful use, but because of the toxicity of thisfamily of compounds, additional treatment compositions which contain nochromates are becoming more and more desirable. With the foregoingobjectives in mind, applicants commenced a comprehensive researchprogram which led to the discovery as explained hereafter.

GENERAL DESCRIPTION 'OF THE INVENTION It was discovered that theforegoing prerequisites could be attained if the particular systems weretreated with a composition comprising:

(1) A water-soluble acid of phosphorus having (i) at least one OAgrouping attached directly to a phosphorus atom of said acid, where \Arepresents sodium, barium, potassium, ammonium or hydrogen (ii) at leastone substituent group attached to a phosphorus atom of said acidselected from the class consisting of (a) an alkyl of from 1 to 25carbon atoms (b) an alkenyl of from 1 to 25 carbon atoms (c) amononuclear aryl group, and

(d) an aliphatic hydrocarbon substituted mononuclear aryl group whereinthe aliphatic hydrocarbon has from 1 to 20 carbon atoms, or thecorresponding anhydride of said acid, and

(2) At least one corrosion inhibitor selected from the group consistingof a water-soluble zinc compound and mercaptobenzothiazole.

The composition is added to the system in an amount effective tosignificantly inhibit corrosion of the system.

Some of the acids of phosphorus which are to be used according to theinvention may be further described according to the following genericchemical formula:

wherein R is as later defined; X is A or R; Ais hydrogen, sodium,barium, potassium or ammonium and m1 is an integer of from 1 through 3.

It is also intended that the amine and amide compounds containing theacid of phosphorus groupings as defined above may be utilized along withthe sulfonated and mercapto derivatives. R as set forth above may bemore specifically defined as being an alkyl group having from one to 25carbon atoms in the carbon chain (straight or branched), preferably 4 to20 atoms in the carbon chain (straight or branched), and most desirably8 to 10* carbon atoms in the carbon chain (straight or branched), or amono or poly unsaturated alkenyl group having from 1 to 25 carbon atomsin the carbon chain (straight or branched), and most desirably 8 to 10'carbon atoms in the carbon chain (straight or branched), or amononuclear aryl group, or a mononuclear aryl group substituted by oneor more alkyl or alkenyl groups having 1 to 20 carbon atoms in thecarbon chain (straight or branched), preferably 8 to 10 carbon atoms inthe carbon chain (straight or branched).

Moreover it is also beneficial to use a substituted acid of phosphorusof the character referred to above in which ethylene oxide groups havebeen substituted to form adducts, there being from 1 to 50 ethyleneoxide groups in the molecule, preferably from 1 to 30 and most desirablyfrom 1 to 10.

The compositions of the invention should be such as to be fed to thecirculating water in the following concentrations:

(A) 1 to 200 p.p,m. of the substituted acid of phosphorus,

(B) (A) plus zinc ion between 0.5 and 50 p.p.m., preferably 1 to 25p.p.m.,

(C) (B) plus mercaptobenzothiazole between 0.5 and 50 p.p.m., preferably1 to 25 p.p.m.,

(D) (A) plus mercaptobenzothiazole between 0.5 and 50 p.p.m., preferably1 to 25 p.p.m.

It is apparent from the foregoing that when the composition contains theacid of phosphorus in the designated amounts together with either of thecorrosion inhibitors, it contains approximately 66 to by weight of theacid and 20 to 33% of the respective corrosion inhibitor. When bothinhibitors are included in the composition, the

3 composition contains from about 50 to 66% by weight of the acid andfrom 16 to 25% of each of the inhibitors.

The drawings contain representative curves which will be useful inexplaining the invention.

FIG. 1 'isa curve plotting differential average penetration in mils peryear (m.p.y.) as ordinate and treatment concentration in p.p.m. asabscissae showing values for different pHs.

FIG. 2 plots differential average penetration in mils per year asordinate and total treatment concentration in p.p.m. as abscissae forvarious combined treatments of substituted acid of phosphorus (phosphateester), alone, phosphate ester plus zinc and phosphate ester plusmercaptobenzothiazole plus zinc, at pH 6.

FIG. 3 plots differential average penetration in mils per year asordinate and total treatment concentration in p.p.m. as abscissae forvarious combined treatments of substituted acid of phosphorus (phosphateester) alone, phosphate ester plus mercaptobenzothiazole and phosphateester plus mercaptobenzothiazole plus zinc, at pH 7.

There are available on the market a number of different organic estersof acids of phosphorus of which may be mentioned orthophosphoric,monosubstituted orthophosphoric acid and di-substituted orthophosphoricacid respectively which have the formulas:

wherein R is an organic group which is specifically exemplified laterand A is a cation as later defined or hydrogen.

Similar type compounds are formed by substituting for hydrogen groups inpolyphosphoric acid and pyrophosphoric acid e.g. the di-substitutedpyrophosphoric acid has the formula:

| HOH wherein R may be a straight or branched chain alkyl group having acarbon chain length of 1 to 25 carbon atoms, preferably 4 to 20 and mostdesirably 8 to 10'. Thus, for example, the alkyl group can be methyl,ethyl, propyl, butyl, hexyl, octyl, or stearyl. R may also be alkenyl,either mono-unsaturated or poly-unsaturated, having a carbon rangebetween 1 and 25 carbon atoms, straight or branched, and preferablybetween 4 and but most desirably between 8 and 10 carbon atoms. Suitablegroups will be oleyl, linoleyl, linolenyl, ricinoleyl, eleosteryl,octenyl, dodecenyl, hexenyl, and butenyl.

The R group may also be aryl, suitably phenyl. R may also be an alkyl oralkenyl mono-substituted or poly-substituted aryl group, where the alkylor alkenyl substituent has between 1 and 20 carbon atom atoms in thecarbon chain and preferably 8 to 10 carbon atoms in the carbon chain.Suitable examples are cresyl, nonylphenyl, octylphenyl, hexylphenyl,tridecylphenyl, amylphenyl, isoamylphenyl, ethylphenyl, isobutylphenyl,dioctylphenyl, or dinonylphenyl.

Moreover the fundamental organic acid of phosphorus structure can bemodified by inclusion of ethylene oxide in the molecule. While theillustration below shows ethylene oxide substituted in anorthophosphoric acid, it will be understood that other acids ofphosphorus such as polyphosphoric acid can likewise be substituted. Thesubstitution of the ethylene oxide can be either on the nucleus or onthe side chain as shown in the two formulas below:

ROI"OA O (CHzCH2O)xH Nucleus cthoxylation H 1&(0 01120112) XO1O B Sidechain ethoxylation In the above formula, A may be hydrogen, or a cationsuch as sodium, potassium, barium, or ammonium. B may be hydrogen, (CHCH O) H, an ethoxylated alkyl or aryl group of the character of R asabove-defined or cations as referred to for A. In all instances xrepresents a number of from 1 to 50.

These organic phosphoric acids can be further modified by substitutionof other atoms such as nitrogen. Typical amide phosphoric acid estersare shown below:

H O Rah-Lox Primary amide ester 1 ll R-N-P-OA Secondary amide esterwherein R and A are as above defined.

Similar compounds of sulphur can be produced in which the sulphurperforms either a bridging role or is in an isolated position as shownbelow:

0 RSl -O A Bridging role II R OIIO A Isolated role Here again the second0A group can be replaced by an RS group to form a di-substituted esterand again R and A are as above-defined.

The preparation of these organic acids of phosphorus is disclosed in theliterature. It involves the reaction of an organic compound containingan active hydrogen such as an alcohol with a phosphating agent such asphosphorus oxychloride, phosphorus trichloride, phosphorus pentoxide,115% phosphoric acid, phosphoric acid or 75% phosphoric acid undercontrolled conditions as described in the art. The preferred organiccompound is an ethoxylated aliphatic alcohol or ethoxylated alkylphenol. (See US. Pats. 3,004,056, 3,004,057 and 3,033,- 889 andTechnical Publication-FMC Technical Data on FMC Superphosphoric Acid105% and FMC Polyphosphoric Acid published by FMC COrporation, InorganicChemicals Division.)

Similarly, ethoxylated amines, amides, and other similar activehydrogen-bearing compounds may be used in place of the alcohol.

The quantity of ethylene oxide per molecule of the organic acid ofphosphorus will suitably range from 1 to 50 mols, preferably 1 to 10mols, and most desirably 1 to mols.

A typical ethoxylated di-substituted acid of phosphorus is shown in thefollowing generic formula:

wherein R and A are as above-defined and x equals from 1 to 50.

As a specific and preferred acid of this type may be exemplified II IICH3(OH2)7O CHzCHz-O POP 0-011201120 oHmom Typical formulas for variousorganic substituted acids of phosphorus where R is alkyl-aryl are shownin the following formulas.

I? i O1|OA O1I0A 0 A O A Alkyl-aryl orthophosphate Dialkyl-arylorthophosphate wherein R represents an aliphatic group of from 1 to 20carbon atoms and A is as above defined.

Particularly suitable acids of phosphorus which are beneficially usedaccording to the present invention are the amine derivatives of theorganic acids of phosphorus which fall within the following genericformula:

wherein R represents a substituted or unsubstituted lower alkylene groupof from 1 to 4 carbon atoms such as methylene, ethylene, propylene andbutylene, X and Y are selected from the group consisting of hydrogen andan alkyl group of from 1 to 4 carbon atoms and A represents hydrogen, acation such as sodium, potassium, barium and ammoniumor combinationsthereof. Compounds which have been found to be quite satisfactory arethose wherein R is methylene, X and Y and A are hydrogen and homologuesof this compound. The results obtainable using the preferred compoundare described later in this specification and are included in theappropriate table which follows.

Various organic acids of phosphorus were evaluated for corrosionprotection under various test conditions comparable to those in anindustrial water system such as a cooling water system and found to haveworthwhile features as set forth below.

The effort was to test the corrosiveness of the water system from thestandpoint both of steel parts and also copper base alloy parts incontact therewith.

The following test conditions which for convenience are numbered, wereused in different experiments:

Test Condition 1 Test Condition 2 This differed from Test Condition 1 inthe following respects, all other features being the same:

Spinner system-Volume 7 liters Flow rate0.64 ft. per second Testspecimens3 high carbon steel specimens as above described and oneadmiralty specimen on each test TreatmentDescribed in pertinent tableTest Condition 3 This differed from Test Condition 2 in the followingrespects and in all other features was the same as Test Condition 2:

pH--Described in pertinent table Duration of test-1 to 3 daysBl0wd0Wn-50% daily Test Condition 4 This was the same as Test Condition3 except in the following features:

Spinner system-Volume 24 liters Flow rate1.5 ft. per second TestCondition 5 This was the same as Test Condition 1 except as noted below:

Recirculating systemVolume 43 liters Flow rate-20 ft. per secondDuration of test--1 to 3 days TreatmentDescribed in pertinent tableBlowdown44.5% daily Test specimens-High carbon steel and Admiraltymetal; heat transfer tube of low carbon steel (AISI 1010), and wattageof heater 1300* Test Condition 6 This was the same as Test Condition 1except as noted below:

Spinner system-22 to 24 liters pH-6 to 7.5 as shown in the pertinenttables Duration of test1 to 3 days Blowdown5 0*% dailyTreatmentDescribed in pertinent tables Water characteristics-Same asTest Condition 1 except as noted in table Test Condition 7 This conformswith Test Condition 5 except for the following changes:

Duration of testl to 7 days as explained in the table Testspecimens-0nly high carbon steel as above Test Condition 8 This testcondition is the same as Test Condition 6 except as noted below:

Spinner systemVolume 22 liters pH7.0 except where noted in the table 7USE OF ORGANIC ACID OF PHOSPHORUS ALONE Using Test Condition 1, thecontrol corrosion rate was found to be 123 mils per year (m.p.y.). Table1 records the results of testing various organic phosphates under TestCondition 1.

TABLE 1.ORGANIC PHOSPHATES AS CORROSION INHIBITORS [Test Condition 1]Moles ethylene Corro- Sanroxide sion Test; p10 per rate, No. No.Compound name General structure chain m.p.y.

1 Control (no treatment). 123 119 Methyl Orthophosphate (RO)PO(O )2 3616 Amyl orthoph0sphate )2 0 29 18 Isoctyl orthophosphate (R0)P0(O )2 015 120 Oleyl orthophosphate (RO)PO(O )2 0 36 38 Diisoamylorthophosphate. (RO)2PO(OHg 0 75 35 Diisooctyl 0rth0ph0sphate (RO)2PO(OH0 21 97 Dldecyl orthophosphate (RO)2PO(OH) 0 46 Ethylrosinorthophosphate". (RO)PO(OR) (OH) 0 3 7 riphenyl orthophosphate (R0 3P0 I0 95 8 Cresyldiphenyl orthophosphate (RO)PO(OR )2 0 103 78 Decylorthophosphate (etlroxylated) (RO)PO(O[C2H4O]1H) (OH) 4 9 7 Potassiumsalt of item 12 (RO)P0(O[C2H40]1H)(OH) 4 1 5 octyl orthophosphate(ethoxylated) (RO)PO(O[C2H4O]XI1)2 1-10 95 80 Nonylphenyl (ethoxylated)orthophosphate (R[C2H4O]X0)P0(OH)2 6 4 90 do A (RlC2 4O]XO)PO(OH)2 9 4783 (lo r (R[C2H4O XO)PO(OH)2 44 95 ridecyl (ethoxylated) orthophosphate(RlC2HrO]10)PO(0 )2 1O 55 87 Dinonylphenyl (ethoxylated) orthophosphate2 4 ]x )2 4 7 88 Barium salt of item 18 (R[CzH4O]XO)IO(OH)2 4 20 92Dinonylphenyl (ethoxylated) orthophosphate I. (R[CQI'I4O]XO)PO(OH)2 6 628 arium salt of item 21 (R[C2H4O]XO)PO(OH)2 6 5 10 Dmonylphenyl(ethoxylated) orthophosphate (R[C2H4O]x )2 10 32 113 Dilauryl(ethoxylated) orthophosphate (R[C2H4O]1O)2PO(OH) 4 45 114 Trilauryl(ethoxylated) orthophosphate (R[C2H40]xO)aPO 4 109 3 Tristearyl(ethoxylated) orthophosphate (RlCzILO X0)al?0 4 103 4 ethyl(ethoxylated) polyphosphate (R[C2H40]x)2(0)(PO3H)3 1-10 72(RlC2H40]X)2(O) (POaI'Da 1-10 92 (R[C2H4O]x)2(0) (POaH)a 1 18 (RIC? 4O])2(O (PO3H) 1-10 19 (RO)[PO(OH) (O)PO(OH)](OR) 0 13 s a5(PsOro)2 O 3R5Nas(PaO1o)2 0 3 )2( s )a 0 O (R)2(0) (POaH)a 0 3 )2( a )s 0 12(R)2(O)(PO3H) 0 1 a )a 0 z [(HO)PO(O)PO(OR)]4OZ 0 9 Partial potassiumsalt of hydrolized item 39". [(HO)PO(O)PO(OR)] O 0 3 Same as item 39 butB group larger than 010 O(O )]4O2 0 54 60 Droctyl (ethoxylated)polyphosphate, amino group present 5 61 Same as item 42, B group ismixed branched 5 22 62 me as item 42, R grou is nondecyl 5 8rlethanolamine phosphate (HO[C2H4]3N0 PO(OH)2 0 19 29 Stearamidopropyldimethyl-B hydroxyethyl ammonium phosphate [RC(O)NHC H N(CH )2C2HO]+H PO 0 11 4 A ino-tri (methyl phosphonic acid) N [CH2PO(OH)2]; o 17 5ent sodium salt of item 47 N[CH2PO(OH)Z] 0 15 7 Octylphenylorthophosphate, sulfonated 0 g Tests 2 to 11 of Table 1 show the resultsof testing unethoxylated orthophosphate esters. Various mono and diesters of orthophosphoric acid were tested, these compounds beingadmixtures of mono and di esters. The most effective results are shownin Tests 4 and 7, where the carbon chain length was 8 carbon atoms. Itis interesting to note that the triester are counter-indicated, itevidently being important that esterification should not be complete.

Tests 12 to 14v of Table 1 show the results obtained where theorthophosphates were ethoxyelated in the nucleus. Unusually good resultswere obtained in Tests 12 and 13 where R was decyl. Test 14 again showsthe counter indication of complete esterification.

Tests 15 to 26 of Table 1 show the results of testing orthophosphateswhere ethoxylation was on the chain as shown in the formulas given.Conversion of the compound to a barium salt was proved to be beneficial.Triesters are counter indicated in Tests and 26.

Tests 27 to 41 of Table 1 show the results of testing various pyroandpolyphosphate esters. Carbon chain lengths for R of between 8 and 10carbon atoms appear optimal. Excellent results were obtained in Tests32, 33, 34, 35, 37, 38, 39, and 40.

Tests 42 to 48 of Table 1 show results for organic aminoand amidophosphates. Good results were obtained even for short chain R groups asin Tests 45, 47 and 48.

USE OF OTHER ADDITIVES An attempt was made to evaluate the effect oforganic acids of phosphorus when used conjointly with other inhibitorssuch as zinc ion and mercaptobeuzothiazole singly or in combination.

Table 2 evaluates under Test Condition 2 various organic acids ofphosphorus fed to provide 50 p.p.rn. alone in the test water, and fed toprovide in the test water the following combinations:

46 ppm. organic phosphate plus 4 p.p.rn. zinc ion 44 p.p.rn. organicphosphate, 4 p.p.rn. zinc ion and 2 p.p.rn. mercaptobenzothiazole 48p.p.rn. organic phosphate, 2 p.p.rn. mercaptobenzothiazole Beforeproceeding to these specific examples it appears appropriate to bringout the fact that when the respective tables and explanation thereforerefers to p.p.m. of

zinc ion, this is what is intended. If a water soluble salt of zinc suchas zinc chloride is added to system treated or to produce thecomposition, the amount of zinc salt added is such as to produce thedesignated amount of zinc ion which in essence is the corrosioninhibitor.

TABLE 2.-ORGANIC PHOSPHAIES (OP) AS CORROSION INHIBITORS,

EVALUATION OF ADDITIVES [Test Condition 2, Corrosion Rates, m.p.y.]

44 p.p.m. (OP), 50 p.p.m. 46 p.p.m. (OP), 4 p.p.m. Zn, 48 p.p.m (OP),(OP) 4 p.p.m. Zn 2 p p.m. MBT 2 p.p.m MBT 1 Refers to Compound Test Nos.in Table 1.

The test results in mils per year penetration for the high carbon steelspecimen are shown in each case in Table 2. Penetration on admiraltymetal was uniformly low for each test ranging from 0 to 6 mils per year.The feed was on a 100% active inhibitor basis, but when activity was notknown it was assumed to be 100%.

Benefit gradually resulted as shown in Table 2 from using zinc ion withthe organic phosphate (Labelled OP). There was also benefit from usingthe organic phosphate in combination with zinc andmercaptobenzothiazole. The benefit resulting from the use ofmercaptobenzothiazole with the organic phosphate was distinct in mostcases.

Tables 3, 4 and 5 and FIGS. 1, 2 and 3 report tests of the organicderivatives with the acids of phosphorus with other additives under TestCondition 3. In all cases the corrosion rate of admiralty metalspecimens was acceptably low. Tests were also made, not reported inthese tables, on corrosion inhibition of the test agents on steel innon-aerated water. The results were just as favorable.

Table 3 shows definite benefit in the case of dioctyl (l-ethylene oxideadduct) pyrophosphate taken with mercaptobenzothiazole and with zincion. Tests l-3 show control results. Test 4 shows the inhibitory efiectof 50 concentration of 27 p.p.m. The benefits of combinations arefurther shown in Tests 9-16 at total treatment levels of to p.p.m.

Tables 4 and 5 show similar benefits when the organic phosphate isdiisooctyl (1 ethylene oxide adduct) pyrophosphate or nonylphenyl (6ethylene oxide adduct) orthophosphate, respectively.

FIG. 1 plotted for dioctyl (l-ethylene oxide adduct) pyrophosphate showsthat inhibition increases generally liner-ally at pH 6, 7 and 8 in therange between 25 and 150 p.p.m. The effectiveness of the treatment isincreased by increasing the pH from 6 to 8.

FIGS. 2 and 3 plot the results from using dioctyl (1- ethylene oxideadduct) pyrophosphate alone and with mercaptobenzothiazole, with zincion and with zinc ion plus mercaptobenzothiazole. Distinct benefits areobtained from using mercaptobenzothiazole plus the acid of phosphorus,but greater benefit is obtained by using the acid with zinc ion andstill much greater benefit is obtained by using the acid with zinc ionand mercaptobenzothiazole. FIG. 2 shows results at pH 6 and FIG. 3 showsresults at pH 7.

TABLE 3.EVALUATION OF DIOCTYL (1 ETHYLENE OXIDE ADDUCT) PYROPHOSPHATEMERCAPTOBENZOTHIAZOLE AND ZINC COMBINA- TIONS [Test Condition 3] DioctylTreatment Concentration p.p.m. Differential Average Penetration Dioctyl(1 ethylene Mercaptooxide adduct) benzothi- M.p.y. at pH M.p.y. at pH 67 [Test Condition 3] Treatment Concentration, p.p.m.

Diflerential Diisooctyl average (1 ethylene Mercaptopenetratlon, oxideadduct) benzom.p.y. pyrophosphate thiazole Zinc at pH 7 TABLE5.EVALUATION OF NONYLPHENYL (6 ETHYL- ENE OXIDE ADDUCT) ORTHIOPHOSPHATE, MERCAP- TOBENZOTHIAZOLE AND ZINC COMBINATIONS [TestCondition 3] Treatment Concentration, p.p.m.

1 Product is 60% nonylphenyl (6 ethylene oxide adduct) orthophosphateplus 40% nonylphenol (6 ethylene oxide adduct).

It is evident that there is synergism in the use of the organic acid ofphosphorus (orthophosphate, pyrophosphate and polyphosphate) withmercaptobenzothiazole and zinc, and with mercaptobenzothiazole alone andwith zinc alone in the case of pyrophosphates and polyphosphates butless benefit is derived in the case of orthophosphates.

Table 6 evaluates amino-tri-(methyl phosphonic acid) alone and withmercaptobenzothiazole and zinc ion. The tests reported in Table 6 wereperformed under Test Condition 4.

Tests 1-4 illustrates the efiective concentrations of the compound whileTests 5 and 6 shows that pH was not significant between pH 6 and pH 7.5.High hardness level in Test 7 was not significant. The addition of zincion in Tests 8-9 was beneficial in lowering the critical treatmentconcentration.

Employment of the organic phosphate ester with mercaptobenzothiazolealone was not as effective as the combination of the organic phosphateester with mercaptobenzothiazole and the Zinc ion, which combination wasvery successful as shown in Tests 12-13.

TABLE 6.AQ,UEOUS CORROSION INHIBITION BY AMINO- TRI (METHYL PHOSPHONICACID) [Test Conditions 4 and 5] Treatment Concentration, p.p.m.

Amino-tri Difi'erential (methyl Mercaptoaverage phosphonicbenzopenetration, acid) thiazole Zinc p m.p.y.

Test No 1 O 0 0 7. 0 168 2. 25 0 0 7. 0 14 3 0 0 7. O 2 4. 150 0 0 7. 02 5. 50 0 0 6. 0 3 6. 1 50 0 0 7. 5 2 7 1 50 0 0 7.0 4 8 21 0 4 7. 0 39. 15 0 1O 7. 0 3 10 47 3 0 7. 0 14 ll. 42 8 0 7. 0 18 l2 42 3 5 7. 0 113 21 1. 5 2. 5 7. 0 3

1 Test performed on water having 850 ppm. Ca as 09.003, 550 ppm. Mg asC3003, 560 p.p.1:n. Cl and 512 p.p.m. S04.

Table 7 shows test results under Test Condition 6 obtained from amixture of octyl polyphosphates.

Table 7 evaluates the corrosion results for octyl polyphosphate,monosubstituted and 40% disubstituted, when fed alone and when fed withZinc ion, with mercaptobenzothiazole and with mercaptobenzothiazole andzinc ion and at different pH values. Percentages are by weight unlessotherwise indicated in the specifications.

Increases in treatment concentration from 25-75 p.p.m. were helpful inTable 7. Corrosion inhibition was directly proportional to the pH of thesystem as shown by Tests 3-6. At a concentration of 50 p.p.n1. totaltreatment, zinc ion was helpful as shown in Tests 7-8. This inhibitionwas not influenced by lowering the pH. At total treatment levels of 25ppm. the addition of Zinc was also very helpful. Combined treatments ofthe organic acid of phosphorus plus zinc plus mercaptobenzothiazole werevery effective as shown by Test 11. Mercaptobenzothiazole along with theorganic acid of phosphorus was beneficial in Test 12 at a totaltreatment concentration of 50 p.p.m. At a total concentration of 25p.p.m. the combined zinc ion, mercaptobenzothiazole and organic acid ofphosphorus treatment was very effective as shown in Tests l314.

TABLE 7.EVALUATION OF DIO CTYL POLYPHOSPHATE 13 Changes in ionconcentration did not make much difference as shown by Tests 15 and 16.Treatment was also efiective in a nearly deaerated system as shown byTests 17 and 18.

Table 8 reports tests on octylphenyl orthophosphate 14 It will beevident in accordance with the invention that the concentration of theorganic acid of phosphorus in the circulating water will be between 1and 200 p.p.m., preferably between and 100 p.p.m. and most desirablybetween and 50 p.p.m.

which has been sulfonated as an example of the alkylaryl 5 It willfurther be evident that there is an advantage sulfonate type of organicacid of phosphorus. The tests in feeding with the organic acid ofphosphorus either were run under Test Condition 8. In Test 2 inhibitioni admixture with or as a separate concurrent feed, to was good. In test3 there was no indication that increased maintain in the circulatingwater from .5 to 50 p.p.m. of ion content affected inhibition. As shownby Test 4, zinc ion, and/or from 0.5 to 50 p.p.m. of mercaptothe removalof oxygen did not change the result. The 10 benzothiazole. addition ofzinc ion was beneficial inTest 5. It' will also be evident that in somecases the organic Table 9 hows test results obta ned on decyl polyacidof phosphorus may be fed conjointly with the zinc phosphoric acid esteranhydride. The test conditions are ion and/ or mercaptobenzothiazole,preferably in the same those set forth in Test Condition 2. Tests 2 to 4show blend but permissibly concurrently and separately. that at a feedof 75 p.p.m., decyl polyphosphate anhydride It will further be evidentthat there is an advantage in inhibited corrosion eifectively. Theaddition of 2 p.p.m. using a pyro or a polyphosphate, althoughorthophosof zinc ion was beneficial as shown in Test 5. The use ofphates may be used with benefit. the Organic Polyphosphate anhydrideWith m r p z It will further be evident that where a water solublethiazole was effective as shown in Test 6' and the addition salt of theacid of phosphorus is used, it may often be of zinc ion to thiscombination was beneficial as shown a sodium salt, potassium salt,ammonium salt, amine in Test 7. When the pH was reduced to 6.0 thisthree salt or preferably a barium salt. compound treatment was quiteeffective as shown in It will further be evident that the organic acidof phos- Test 8. Change in hardness level did not makeasignificantphorus will often be substituted by 1 to 50 moles of difference as shownby Tests 9 and 10. The absence of ethylene oxide, preferably 1 to 10moles and most desiroxygen did not adversely affect the inhibition asshown ably 1 to 5 moles. by Tests 11 and 12. In view of our inventionand disclosure, variations and TABLE 8 COOL1NG W ATER CORROSIONINHIBITION BY IIlOdlfiCfllllOl'lS to meet individual WhlIll OIparticular need OCTYLPHENYL ORTHOPHOSPHATE SULPHONATED will doubtlessbecome evident to others skilled in the art [Test Condition to obtainall or part of the benefits of our invention Comm without copying theprocess and composition shown, and tration,p.p.mwe, therefore, claim allsuch insofar as they fall within octylphenyl Comsion the reasonablespirit and scope of our claims. o t op o p e rate. Having thus describedour inventlon what we claim as Sulphonated Zmc Water condltms new anddesire to secure by Letters Patent is:

0 0 Normal 168 1. A process for inhibiting the corrosion of metal parts3 0 IIIII: 13 in contact with a water system, which comprises feeding 3g8 gg ggg gl gf f g into the water system a composition consistingessense 2 Normal 7 3! 0f 40 (1) a water soluble acid of phosphorushaving TAB LE [Test Condition 2] Treatment Concentration, p.p.m.

9.COMPREHENSIVE EVALUATION OF DECYL POLYPHOSPHATE ANHYDRIDE Decyl poly-Mercapt 0- Temper- Corrosion phosphate benzoature, I rate, anhydrideZinc thiazole pH F. Water characteristics m.p.y.

0 0 0 7 120 Normal 101 0 0 7 d0 5 75 0 0 7 do 10 75 0 0 7 do 12 73 2 0 7120 do. 5 73 0 2 7 120 do 4 71 2 2 6 120 do 3 71 2 2 7 120 do 2 75 0 0 7120 0 p.p.m. hardness 10 75 0 0 7 120 5X normal hardness"..- 10 75 0 0 79 73 2 0 7 6 100 0 2 7 7 1 Test condition (i) at least one 0A groupingattached directly to a phosphorus atom of said acid, wherein A isselected from the group consisting of hydrogen, barium, sodium,potassium and ammoni- Decyl polyphosphate anhydride at 100 p.p.m. plus 2p.p.m. mercaptobenzothiazole was also evaluated according to TestCondition 7. The test involved five days exposure. The corrosion ratewas a very low 7 m.p.y.

In summary, therefore, it will be seen that decyl poly- 65 um, andphosphate ester anhydride is beneficial as a corrosion (ii) at least onesubstituent group selected from inhibitor and conjoint use with zinc orwith Inercapto the class consisting of benzothiazole or with both isbeneficial. Inhibition occurs (a) an alkyl of from 1 to 25 carbon atoms,at various hardness levels, and with different oxygen (b) an alkenyl offrom 1 to 25 carbon atoms, concentrations and difierent pHs. 70 (c) amononuclear aryl group It will be evident that in the present inventionthe (d) an aliphatic hydrocarbon substituted phosphate compound will beeither an acid of phosphorus mononuclear aryl group wherein thealiand/or a water soluble salt of such an acid, which often phatichydrocarbon has from 1 to 20' carwill be a partial salt, although insome cases it may be bon atoms; or the corresponding anhydride acompleted salt. 75 of said acid, and

(2) at least one corrosion inhibitor selected from the the groupconsisting of a water soluble zinc compound and mercaptobenzothiazole,the ratio of said acid of phosphorus to said corrosion inhibitor beingfrom 400:1 to 1:50 when said corrosion inhibitor is a zinc compoundalone or mercaptobenzothiazole alone, and being from 200:1 to 1:25 whensaid corrosion inhibitor consists of equal parts by weight of zinccompound and mercaptobenzothiazole, said composition being fed into saidsystem in an amount sufiicient to significantly inhibit corrosion.

2. A process according to claim 1 wherein the corrosion inhibitor is azinc compound and wherein from 1 to 200 parts by weight of said acid ofphosphorus per million parts of water and from 0.5 to 50 parts by weightof zinc ion per million parts by weight of water are fed into said watersystem.

3. A process according to claim 1 wherein the corrosion inhibitor ismercaptobenzothiazole and wherein from 1 to 200 parts by weight of saidacid of phosphorus per million parts by weight of water and from 0.5 to50 parts by weight of said mercaptobenzothiazole per million parts ofwater are fed into said water system.

4. A process according to claim 1 wherein the corrosion inhibitor is acombination of the Zinc compound and mercaptobenzothiazole and whereinfrom 1 to 200 parts by Weight of said acid of phosphorus per millionparts by weight of water and from 0.5 to 50- parts by weight of each ofsaid zinc ion and mercaptobenzothiazole per million parts by weight ofweight of water are fed into said water system.

5. A process according to claim 1 wherein the acid of phosphoruspossesses a formula selected from the group consisting of wherein R is amember selected from the group consisting of an alkyl of from 1 to 25carbon atoms, an alkenyl of from 1 to 25 carbon atoms, a mononucleararyl, alkyl substituted mononuclear aryl wherein the alkyl is of from 1to 20 carbon atoms, alkenyl substituted mononuclear aryl wherein thealkenyl is of from 1 to 20 carbon atoms, and A is selected from thegroup consisting of hydrogen, sodium, barium, potassium and ammonium,

wherein R and A are as above-defined and x is an integer of from 1 toS0,

wherein R is as above defined, B is selected from the group consistingof R as above defined, hydrogen, barium, potassium, sodium, ammonium,(CH CH O) H and (CH CH O R wherein R and A are as above defined and x isan integer of from 1 to 50.

wherein R is a lower alkylene group, X and Y are hydrogen or an alkylgroup of 1 to 4 carbon atoms and A is hydrogen, sodium, potassium,barium, or ammonium,

R-iI-ii-OA wherein R and A are as above defined,

R-I I] r 0A wherein R and A are as above defined,

RS-1 OA AA wherein R and A are as above defined, and

R oi o A wherein R and A are as above defined.

6. A process according to claim 5 wherein the acid of phosphorus has theformula wherein A is a hydrogen, sodium, potassium, barium and ammonium.

7. A process according to claim 5 wherein the corrosion inhibitor is azinc compound and wherein from 1 to 200 parts by weight of said acid ofphosphorus per million parts of water and from 0.5 to 50 parts by weightof zinc ion per million parts by weight of water are fed into said watersystem.

8. A process according to claim 7 wherein the acid of phosphorus has theformula wherein A is hydrogen, sodium, potassium, barium and ammonium.

9. A process according to claim 5 wherein the corrosion inhibitor ismercaptobenzothiazole and wherein from 1 to 200 parts by weight of saidacid of phosphorus per million parts by weight of water and from 0.5 to-50 parts by Weight of mercaptobenzothiazole per million parts of waterare fed into said water system.

10. A process according to claim 5 wherein the corrosion inhibitor is acombination of the zinc compound and mercaptobenzothiazole and whereinfrom 1 to 200 parts by weight of said acid of phosphorus per millionparts by weight of water and from 0.5 to 50 parts by weight of each zincion and mercaptobenzothiazole per million parts by weight of water arefed into said water system.

11. A water treatment composition consisting essentially of 1) a watersoluble acid of phosphorus having (i) at least one 0A grouping attacheddirectly to 17 a phosphorus atom of said acid, wherein A is selectedfrom the group consisting of hydrogen, barium, sodium, potassium andammonium, and (ii) at least one substituent group selected from theclass consisting of (a) an alkyl of from 1 to 25 carbon atoms, (b) analkenyl of from 1 to 25 carbon atoms, (c) a mononuclear aryl group (d)an aliphatic hydrocarbon substituted mononuclear aryl group wherein thealiphatic hydrocarbon has from 1 to 20 carbon atoms; or thecorresponding anhydride of said acid, and

(2) at least one corrosion inhibitor selected from the group consistingof a water soluble zinc compound and mercaptobenzothiazole, the ratio ofsaid acid of phosphorus to said corrosion inhibitor being from 400:1 to1:50 when said corrosion inhibitor is a zinc compound alone ormercaptobenzothiazole alone, and being from 200:1 to 1:25 when saidcorrosion inhibitor consists of equal parts by weight of zinc compoundand mercaptobenzothiazole.

12. A water treating composition according to claim 11 which containsfrom about 66 to 80% by weight of said acid of phosphorus and from about33 to 20% by weight of zinc ion.

13. A water treatment composition according to claim 11 which containsfrom about 66 to 80% by weight of said acid of phosphorus and from about33 to 20% by weight of mercaptobenzothiazole.

14. A water treatment composition according to claim 11 which containsfrom about 50 to 66% by weight of said acid of phosphorus, from about 16to 25% by Weight of said zinc ion and from about 16 to 25 by weight ofmercaptobenzothiazole.

15. A water treatment composition according to claim 11 wherein saidacid of phosphorus possesses a formula selected from the groupconsisting of wherein R is a member selected from the group consistingof an alkyl of from 1 to 25 carbon atoms, an alkenyl of from 1 to 25carbon atoms, a mononuclear aryl, alkyl substituted mononuclear arylwherein the alkyl is of from 1 to 20 carbon atoms, alkenyl substitutedmononuclear aryl wherein the alkenyl is of from 1 to 20 carbon atoms,and A is selected from the group consisting of hydrogen, sodium, barium,potassium and ammonium,

ROPA

(CHz-CHzOhH wherein R and A are as above-defined and x is an integer offrom 1 to 50,

wherein R is as above defined, B is selected from the group consistingof R as above defined, hydrogen, barium, potassium, sodium, ammonium,

) H and R wherein R and A are as above defined and x is an integer offrom 1 to 50,

R(OCH2CHz),-O#OI0 (OHzCHzOhR wherein R, A and x are as above defined,

wherein R is a lower alkylene group, X and Y are hydrogen or an alkylgroup of 1 to 4 carbon atoms and A is hydrogen, sodium, potassium,barium or ammonium,

(8) I ll wherein R and A are as above defined,

RI I1l OA wherein R and A are as above defined,

RSiI -0A 0A wherein R and A are as above defined, and

wherein R and A are as above defined.

16. A water treatment composition according to claim 15 wherein the acidof phosphorus has the formula wherein A is hydrogen, sodium, potassium,barium and ammonium.

17. A water treating composition according to claim 15 which containsfrom about 66 to by weight of said acid of phosphorus and from about 33to 20% by weight of zinc ion.

18. A water treatment composition according to claim 17 wherein the acidof phosphorus has the formula wherein A is hydrogen, sodium, potassium,barium and ammonium.

19. A water treatment composition according to claim 15 which containsfrom about 66 to 80% by weight of said acid of phosphorus and from about33 to 20% by weight of mercaptobenzothiazole.

20. A water treatment composition according to claim 15 which containsfrom about 50 to 66% by weight of said acid of phosphorus, from about 16to 25 by weight of said zinc ion and from about 16 to 25 by weight ofmercaptobenzothiazole.

21. A water composition according to claim 14 wherein the acid ofphosphorus is a di (octyl-l-ethylene oxide adduct) pyrophosphate havingthe formula,

(References on following page) 19 20 References Cited RICHARD D.LOVERING, Primary Examiner UNITED STATES PATENTS I. GLUCK, AssistantExaminer 2,900,222 8/ 1959 Kahler et a1 252-387 X 3,133,787 5/1964Kelley 212.7 US. Cl. X.R.

3,222,291 12/1965 Heit et a1. 252-389 5 252-390 Dedication3,510,436.R0nald M. Silverstez'n, Parsippany, N.J., Chester A. Bishaf,North Hills, and Joseph T. Matey, Levittown, Pa. CORROSION INHIBI- TIONIN \VATER SYSTEM. Patent dated May 5, 1970. Dedication filed Nov. 4,1974, by the assignee, Beta Laboratories, Inc. Hereby dedicates to thePublic the entire remaining term of said patent.

[Oflimlal Gazette July 1, 1.975.]

